The use of dyes which filter or absorb radiation to prevent unwanted exposure in radiation-sensitive elements is well known. The dye may be present in the radiation-sensitive layer and/or in a separate, auxiliary layer or layers of a multilayer radiation-sensitive element.
The position of the dye-containing auxiliary layer within the element depends upon its purpose. These layers may be: (1) backing layers, positioned on the side of the support opposite that bearing the radiation sensitive layer or layers; (2) undercoat layers, located between the support and the radiation sensitive layer or layers; (3) interlayers, situated between two radiation sensitive layers; and/or (4) overlayers, located on the outermost surface of the radiation-sensitive layer or layers.
Scattered and reflected incident radiation can cause halation, that is, exposure of the radiation sensitive layer in regions in which exposure is not desired. Dye-containing auxiliary layers, known as antihalation layers, absorb radiation reflected and/or refracted from layer-layer interfaces, the layer-support interface, and/or from the back side of the support.
Dye-containing auxiliary layers may also be used as filter layers, that is, layers which absorb incident radiation in one portion of the spectrum while allowing radiation in other spectral regions to pass through and expose a photosensitive layer. A dye-containing auxiliary layer may absorb all the radiation so that, for example, the emulsion on one side of a radiation-sensitive element is not exposed by radiation incident on the other side of the element.
It is generally important that the dye not migrate from the layer in which it is contained, either during or after manufacture of the radiation-sensitive element. Migration of the dye into the radiation-sensitive layer, for example, could have a deleterious effect on the sensitometry of the radiation-sensitive element.
Since residual dye produces an objectionable stain in the final image, it is also important that the dye be completely discharged or otherwise removed from the radiation-sensitive element during processing. Shortened processing times in, for example, X-ray and microfilm processing systems, have reduced the time available for dye removal.
Mordants, which absorb or bind the dye, are sometimes used to prevent dye migration. Processes using mordants to prevent dye migration have been disclosed in a number of patents, for example, Miyazako, U.S. Pat. No. 3,795,519. However, to prevent dye stain, the mordant must quickly and efficiently release the dye during processing. Factor, U.S. Pat. No. 5,006,450, for example, discloses the use of mordant polymers containing selected cationic groups to prevent dye migration.
Despite the advances which have been made, a need exists for polymers which prevent dye migration, but do not increase development time and/or dye stain.